Please refer to FIGS. 1, 2, and 3 for a traditional ratchet bushing assembly for market-standard bicycles.
The cylindrical bushing 1 is and has an axle hole at its center for receiving an axle rod. A plurality of embedded bars radially fix around the outer wall. A ratchet wheel 2 extends into the bushing 10 having three pawls 3 radially dispersed around its outer wall with the hinged end of each pawl 3 being circular allowing the concave chamber 4 of the ratchet wheel 2 to rotate. The distal end of the pawl 3 is a moveable wedge-shaped tooth.
A seam 5 located inside the perimeter of the ratchet wheel 2 houses a C-shaped retaining ring 6 which forces each pawl 3 to extend outwards such that each unhinged end of a pawl 3 protrudes from the ratchet wheel 2 to catch onto a pawl ring 7. The pawl ring 7 sheathes the ratchet wheel 2 and a screw thread on the outer periphery couples to the drum of the bicycle. A plurality of interdental spaces 8 located on the inner perimeter of the pawl ring 7 corresponds to size of the wedge-shaped tooth of each pawl 3.
When the axle rod is rotated clockwise to turn the bushing 1, each pawl 3 precisely engages with the interdental spaces 8 of the pawl ring 7 to drive the drum to rotate. Conversely, when the axle rod is rotated anticlockwise, each pawl 3 on the outer wall of the ratchet wheel 1 cannot engage with the interdental spaces 8 of the pawl ring 7, such that the pawl ring 7 will run in idle and does not drive the drum to rotate. In other words, a cyclist pedals to drive a bicycle wheel forwards, reversing the pedaling direction has no effect. However, as each pawl 3 at the periphery of the ratchet wheel 2 is pressed by the inner wall of the pawl ring 7, the C-shaped retaining ring 6 is forced outwards such that the external wall of the retaining ring 6 and the inner wall of the pawl ring 7 generates noise from the friction.